[Show abstract][Hide abstract] ABSTRACT: Background. Human papillomavirus (HPV) self-sampling might be a promising tool to increase effectiveness of primary HPV screening programs when offered to non-attendees. However, effectiveness could decrease if regular attendees 'switch' to self-sampling, since self-sampling test characteristics may be inferior. We examined under which conditions the harms would outweigh the benefits. Methods. The MISCAN-cervix model was used to estimate quality-adjusted life years (QALYs) gained and costs of offering HPV self-sampling to non-attendees. We varied the relative CIN2+ sensitivity and specificity (self-sampling versus regular sampling), extra attendance, risk of extra attendees, and the switching percentage. Results. Without switching, offering self-sampling is (cost-)effective under every studied condition. If the attendance due to self-sampling increases by ≥6 percentage points, higher primary background risk women (unscreened women who will never attend regular screening) attend and the relative CIN2+ sensitivity and specificity are ≥0.95, it is (cost-)effective to offer self-sampling to non-attendees, even if all regular attendees switch. If the relative sensitivity decreases to 0.90 combined with either a 3 percentage points extra attendance or the absence of higher primary background risk women, QALYs are lost when more than 30-20% of the regular attendees switch. Conclusions. Offering self-sampling will gain health effects if the relative CIN2+ sensitivity is ≥0.95, unscreened attendees are recruited, and the total attendance increases by ≥6 percentage points. Otherwise, switching of regular attendees may decrease the total effectiveness of the program. Impact. Self-sampling needs to be implemented with great care and advantages of office-based sampling need to be emphasized to prevent switching.
[Show abstract][Hide abstract] ABSTRACT: Knowledge of the natural history of human papillomavirus (HPV), in particular the role of immunity, is crucial in estimating the (cost-) effectiveness of HPV vaccination and cervical cancer screening strategies, because naturally acquired immunity after clearing an infection may already protect part of the risk population against new HPV infections.
We used STDSIM, an established stochastic microsimulation model, quantified to the Netherlands. We explored different assumptions regarding the natural history of HPV-16 and HPV-18, and estimated the transmission probabilities and durations of acquired immunity necessary to reproduce age-specific prevalence.
A model without acquired immunity cannot reproduce the age-specific patterns of HPV. Also, it is necessary to assume a high degree of individual variation in the duration of infection and acquired immunity. According to the model estimates, on average 20% of women are immune for HPV-16 and 15% for HPV-18. After an HPV-16 infection, 50% are immune for less than 1 year, whereas 20% exceed 30 years. For HPV-18, up to 12% of the individuals are immune for less than 1 year, and about 50% over 30 years. Almost half of all women will never acquire HPV-16 or HPV-18.
Acquired immunity likely plays a major role in HPV epidemiology, but its duration shows substantial variation. Combined with the lifetime risk, this explains to a large extent why many women will never develop cervical cancer.
PLoS ONE 02/2015; 10(2). DOI:10.1371/journal.pone.0116618 · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose: To explore the uncertainties of early detection of pancreatic cancer in high-risk individuals and consequently highlight the areas to which further research should be directed.
Method: Effects of pancreatic cancer screening were estimated using the Microsimulation Screening Analysis (MISCAN)-model. The majority of the model assumptions were based on preliminary data from the screening trials, the recommendations as stated in the consensus paper of the international Cancer of the Pancreas Screening (CAPS)-consortium, and expert opinions. We varied dwell times of the different health states and test-characteristics of the screening test. We considered different screening ages and intervals and varied follow-up strategies after a positive screening.
Result: Mortality reduction (MR) was 35% and 58% (436 and 722 cases per 10,000 persons) for 5-yearly and annual screening at ages 50 to 75, respectively. For 5 yearly screening, the number needed to screen (NNS) was 117.1 and number needed to treat (NNT) was 2.5 to prevent one cancer death (see Figure (the order (from left to right) of the variations in the factors (between brackets) corresponds to the order (from left to right) in the figure. The dashed lines represent the results of the base case analyses)). The NNT was lowest in case all screen positives with preinvasive stage 3 or cancer are treated (2.4, MR 32%). If only persons are treated who are already in an invasive stage of disease, the NNT was 5.3 (MR 10%). Results were sensitive for pancreatic cancer risk (risk doubled: NNS 64.3, NNT 2.7, MR 38%) and duration of the preclinical stage of the disease (increased to 30 years: NNS 92.6, NNT 3.2, MR 46%). Results were less sensitive for test characteristics.
Conclusion: Modeling shows that there is potential for pancreatic screening to be cost-effective in high-risk individuals. Follow-up strategy of screen positives and duration of the preclinical stage have the highest impact on the outcome of pancreatic cancer screening, as is inclusion of patient populations that are exposed to a certain risk to develop pancreatic cancer.
The 36th Annual Meeting of the Society for Medical Decision Making; 10/2014
[Show abstract][Hide abstract] ABSTRACT: Purpose:
Since empirical utility scores are now available for all health states related to cervical cancer screening and treatment, we estimated the impact of using these utility scores on the cost-effectiveness of cervical cancer screening, compared to using utility scores from the literature.
We first reviewed the literature on cost-effectiveness analyses (CEAs) of cervical cancer screening published between 2003 and 2013. We focused on studies that used quality adjusted life years (QALYs). We evaluated the differences in utility assumptions between the publications. For the different CEAs and based on the empirical data, we calculated the number of days lost due to loss of quality of life for the different health states, by multiplying the assumed utilities with the mean durations of the loss in quality of life.
We used the microsimulation screening analysis (MISCAN) model to estimate the impact of using these different utility scores on the cost-effectiveness (costs per QALY gained) of primary human papillomavirus (HPV) screening compared to no screening.
Utility scores and number of days lost due to loss of quality of life as assumed for women in different health states that are related to cervical cancer and its prevention are very heterogeneous across the different CEAs, as well as compared to the empirical data. These differences result in a significant variation in cost-effectiveness of primary HPV screening compared to no screening, ranging from 8,035 to 13,518 per QALY gained (See Figure). If the empirical data was used, the cost effectiveness of primary HPV screening was 11,839 per QALY gained.
The assumed number of days lost as a consequence of loss in quality of life for different health states in CEAs of cervical cancer screening has a major effect on the estimated cost-effectiveness ratio of screening. We showed that most CEAs, compared to the empirical data, overestimated the number of QALYs gained by screening, and therefore overestimate the cost effectiveness of screening. Utility assessment in CEAs therefore needs to be based on good quality data. From our analysis, we can conclude that for comparability, extensive sensitivity analyses on quality of life assumptions and presentation of costs per life year gained in CEAs are needed.
The 35th Annual Meeting of the Society for Medical Decision Making; 10/2013
[Show abstract][Hide abstract] ABSTRACT: Cervical cancer screening with liquid-based cytology (LBC) has been developed as an alternative to the conventional Papanicolaou (CP) smear. Cost-effectiveness is one of the issues when evaluating LBC. Based on the results of a Dutch randomised controlled trial, we conducted cost-effectiveness threshold analyses to investigate under what circumstances manually screened ThinPrep LBC is cost-effective for screening.
The MISCAN-Cervix microsimulation model and data from the Dutch NETHCON trial (including 89,784 women) were used to estimate the costs and (quality-adjusted) life years ((QA)LYs) gained for EU screening schedules, varying cost-effectiveness threshold values. Screening strategies were primary cytological screening with LBC or CP, and triage with human papillomavirus (HPV) testing.
Threshold analyses showed that screening with LBC as a primary test can be cost-effective if LBC is less than 3.2 more costly per test than CP, if the sensitivity of LBC is at least 3-5 % points higher than CP, if the quality of life for women in triage follow-up is only 0.39, or if the rate of inadequate CP smears is at least 16.2 %.
Regarding test characteristics and costs of LBC and CP, only under certain conditions will a change from CP to manually screened ThinPrep LBC be cost-effective. If none of these conditions are met, implementation of manually screened ThinPrep LBC seems warranted only if there are advantages other than cost-effectiveness. Further research is needed to establish whether other LBC systems will be more favorable with regard to cost-effectiveness.
Cancer Causes and Control 06/2012; 23(8):1323-31. DOI:10.1007/s10552-012-0011-1 · 2.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate, using a Dutch model, whether and under what variables framed for other European countries screening for human papillomavirus (HPV) is preferred over cytology screening for cervical cancer, and to calculate the preferred number of examinations over a woman's lifetime.
Cost effectiveness analysis based on a Dutch simulation model. Base case analyses investigated the cost effectiveness of more than 1500 different screening policies using the microsimulation model. Subsequently, the policies were compared for five different scenarios that represent different possible scenarios (risk of cervical cancer, previous screening, quality associated test characteristics, costs of testing, and prevalence of HPV).
Various European countries.
Unvaccinated women born between 1939 and 1992.
Optimal screening strategy in terms of incremental cost effectiveness ratios (costs per quality adjusted life years gained) compared with different cost effectiveness thresholds, for two levels of sensitivity and costs of the HPV test.
Primary HPV screening was the preferred primary test over the age of 30 in many considered scenarios. Primary cytology screening was preferred only in scenarios with low costs of cytology and in scenarios with a high prevalence of HPV in combination with high costs of HPV testing.
Most European countries should consider switching from primary cytology to HPV screening for cervical cancer. HPV screening must, however, only be implemented in situations where screening is well controlled.
[Show abstract][Hide abstract] ABSTRACT: This article compares cervical cancer screening intensity and cervical cancer mortality trends in the United States and the Netherlands to illustrate the potential of cross-national comparative studies. We discuss the lessons that can be learned from the comparison as well as the challenges in each country to effective and efficient screening.
We used nationally representative data sources in the United States and the Netherlands to estimate the number of Pap smears and the cervical cancer mortality rate since 1950. The following questions are addressed: How do differences in intensity of Pap smear use between the countries translate into differences in mortality trends? Can population coverage rates (the proportion of eligible women who had a Pap smear within a specified period) explain the mortality trends better than the total intensity of Pap smear use?
Even though three to four times more Pap smears per woman were conducted in the United States than in the Netherlands over a period of three decades, the two countries' mortality trends were quite similar. The five-year coverage rates for women aged thirty to sixty-four were quite comparable at 80 to 90 percent. Because screening in the Netherlands was limited to ages thirty to sixty, screening rates for women under thirty and over sixty were much higher in the United States. These differences had consequences for age-specific mortality trends. The relatively good coverage rate in the Netherlands can be traced back to a nationwide invitation system based on municipal population registries. While both countries followed a "policy cycle" involving evidence review, surveillance of screening practices and outcomes, clinical guidelines, and reimbursement policies, the components of this cycle were more systematically linked and implemented nationwide in the Netherlands than in the United States. To a large extent, this was facilitated by a public health model of screening in the Netherlands, rather than a medical services model.
Cross-country studies like ours are natural experiments that can produce insights not easily obtained from other types of study. The cervical cancer screening system in the Netherlands seems to have been as effective as the U.S. system but used much less screening. Adequate coverage of the female population at risk seems to be of central importance.
[Show abstract][Hide abstract] ABSTRACT: Purpose: To assess determinants of parental intention, prior to their decision about their daughter’s uptake of Human Papillomavirus (HPV) vaccination.
Method: In June 2009 self-administered questionnaires were spread among 5918 parents with a 10 to 11-year-old daughter, assessing their uptake intention; knowledge about HPV vaccination; attitudes toward vaccination; and other determinants. Knowledge scores ranged from 0-18, with scores of ≥ 10 indicating sufficient decision-relevant knowledge. Rates of informed intention were measured, i.e. an intention that is in line with attitudes and based on sufficient HPV decision-relevant knowledge. An ordinal logistic regression model was used to determine predictors of intended HPV uptake. An interaction between attitude and knowledge was included in the model.
Result: The response rate was 29.8% (1762/5918). Multivariate analyses showed that a higher intention was determined by trust in the HPV vaccine (OR 2.03; 95%CI: 1.64-2.51), anticipated regret in case of no vaccination uptake (OR 1.68; 95%CI: 1.49-1.89), trust in the National Immunization Program (NIP) (OR 1.26; 95%CI: 1.01-1.57), and the belief that according to significant others their daughter should be vaccinated, and the motivation to comply to that (OR 1.05; 95%CI: 1.04-1.08). Higher perceived parental responsibility for their daughter’s health was related to a lower uptake intention (OR 0.60; 95%CI: 0.45-0.82). There was a significant interaction between attitude and knowledge (OR 1.07; 95%CI 1.03-1.11), meaning that at higher knowledge levels the relation between attitude and intention was stronger. Demographic characteristics, perceived susceptibility of mother and daughter to contract cervical cancer and severity of cervical cancer were not associated with intention. Less than half of the respondents (48%) made an informed intention.
Conclusion: The present findings suggest that the relation between attitude and intention was stronger at higher knowledge levels. Increasing adequate HPV relevant knowledge may be vital to ensure attitude-consistent informed decision-making. Nevertheless, the present study also underscores the role of trust in the vaccine and NIP, and anticipated regret, thus affective feelings may play an even more prominent role in situations of uncertainly.
The 33rd Annual Meeting of the Society for Medical Decision Making; 10/2011
[Show abstract][Hide abstract] ABSTRACT: Purpose: In the Netherlands 12-year-old girls are offered the HPV vaccine free of charge and are legally entitled to take their own decision about vaccination uptake. To inform girls about HPV vaccination, they are sent a standardized information leaflet prior to the vaccination offer. While it is important that girls have decision-relevant knowledge – and can make an informed choice about uptake - it is unknown to which extent relevant information, e.g. the extent and duration of protection against cervical cancer through vaccination, is understood after reading the leaflet.
Method: A questionnaire was completed by 11 to 14-year-old girls at school. To assess whether completing a pre-test would trigger attentively reading the leaflet, respondents were randomly assigned to one of two groups: the intervention group completed a pre-test, read the leaflet and completed a post-test; the control group only read the leaflet and completed a post-test. In both pre and post-test we assessed knowledge about HPV (statements to be answered with ‘true’ or ‘false’); attitudes; and intentions towards having the vaccination. Knowledge scores ranged from 0-10, with scores of ≥ 6 indicating sufficient decision-relevant knowledge.
Result: The response was 237/287 (83%). After reading the leaflet the average knowledge score in the intervention group increased from 5.3 to 7.2 out of 10 (P<0.001). In the post-test 37% knew that HPV vaccinations do not protect completely against cervical cancer and 29% answered correctly that we don’t know for a fact that HPV vaccinations will protect against cervical cancer for a life-time. The rate of informed intentions about uptake increased from 21.9% at pre-test to 68.1% at post-test. The average knowledge score in the control group of 6.3 in the post-test was significantly lower than that of the intervention group. 36.3% of uptake intentions in the control group could be considered informed.
Conclusion: This study showed that although an information leaflet had a positive effect on the correspondence between attitude and intention, and on girls’ knowledge of HPV, knowledge about the degree and duration of protection against cervical cancer remained low. Inclusion of a control group allowed us to assess the effect of a pre-test on knowledge scores. By editing the leaflet and emphasizing these aspects, awareness of the degree and unknown duration of protection can be raised.
The 33rd Annual Meeting of the Society for Medical Decision Making; 10/2011
[Show abstract][Hide abstract] ABSTRACT: To call attention to the influence of the number of birth-cohorts used in cost-effectiveness analysis (CEA) models on incremental cost-effectiveness ratios (ICERs) under differential discounting.
The consequences of increasing the number of birth-cohorts are demonstrated using a CEA of cervical cancer prevention as an example. The cost-effectiveness of vaccinating 12-year-old girls against the human papillomavirus is estimated with the MISCAN microsimulation screening analysis model for 1, 10, 20, and 30 birth-cohorts. Costs and health effects are discounted with equal rates of 4% and alternatively with differential rates of 4% and 1.5% respectively. The effects of increasing the number of cohorts are shown by comparing the ICERs under equal and differential discounting.
The ICER decreases as the number of cohorts increases under differential discounting, but not under equal discounting.
The variation of ICERs with the number of cohorts under differential discounting prompts questions regarding the appropriate specification of CEA models and interpretation of their results. In particular, it raises concerns that arbitrary variation in study specification leads to arbitrary variation in results. Such variations could lead to erroneous policy decisions. These findings are relevant to CEA guidance authorities, CEA practitioners, and decision makers. Our results do not imply a problem with differential discounting per se, yet they highlight the need for practical guidance for its use.
Value in Health 06/2011; 14(4):438-42. DOI:10.1016/j.jval.2010.09.009 · 2.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We explored trends in incidence and mortality of cervical cancer by age, stage and morphology, and linked the observed trends to screening activities. Data was retrieved from the Netherlands Cancer Registry during 1989-2007 (incidence) and Statistics Netherlands during 1970-2007 (mortality). Trends were evaluated by calculating the estimated annual percentage change (EAPC). Joinpoint regression analysis was used to detect changes in trends. Cervical intraepithelial neoplasia (CIN) detection rates were calculated by data from "the nationwide network and registry of histo- and cytopathology" during 1990-2006. Total age-adjusted incidence rate (European standardized rate (ESR)) was 7.9 per 100,000 woman years in 2007. During 1989-1998, incidence rates decreased with an EAPC of -1.3% (95% confidence interval (CI) -2.2 to -0.3), during 1998-2001 with -6.7% (95% CI: -16.4 to 4.1), and increased during 2001-2007 with 2.3% (95% CI: 0.4 to 4.2). Total mortality ESR was 1.9 per 100,000 woman years in 2007. Mortality rates decreased during 1970-1994 annually with -4.1% (95% CI: -4.6% to -3.7%), and with -2.6% (95% CI: -3.8% to -1.5%) during 1994-2007. The observed trend in total incidence is similar to the trend in squamous cell carcinomas in age group 35-54 years, suggesting that the observed trends are likely to be associated to changes in the screening program. This is supported by the trend in CINIII detection rates. In conclusion, incidence and mortality overall decreased and leveled off. On top of that there was an extra decrease that was compensated by a following recent increase in incidence, probably resulting from reorganization of the Dutch screening program.
International Journal of Cancer 05/2011; 128(9):2174-81. DOI:10.1002/ijc.25553 · 5.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Besides cervical cancer, the human papillomavirus (HPV) is found in other cancers and may be preventable with HPV vaccination. However, these other cancers are often not accounted for in cost-effectiveness analyses of HPV vaccination. This study estimates the potential maximum effect on the cost-effectiveness ratio (CER) of HPV vaccination in preventing non-cervical HPV-positive cancers. For the Dutch situation, a mathematical equation was used to estimate the maximum impact if all cancer cases of the penis, vulva/vagina, anus, oral cavity and oro-pharynx with HPV16/18 are prevented, in terms of number of life years gained, savings and improvement in the CER of the vaccination. For other countries and for future developments, we show how the impact on the CER varies depending on the incidence of cervical/non-cervical HPV 16/18-positive cancers, vaccine costs and clinical costs. If in the Netherlands all HPV 16/18-positive cancers are prevented by vaccination in women only, compared to if only HPV 16/18-positive cervical cancer is prevented, the life years gained increase with 14%, the savings increase with 18%, and the CER decreases with 13%. If vaccination prevents HPV-positive cancers in both men and women, these figures increase to 25%, 26% and 21%, respectively. In conclusion, if HPV vaccination fully prevents all non-cervical HPV-positive cancers, this would substantially increase its cost-effectiveness. The impact of the vaccination varies depending on the incidence of cervical/non-cervical HPV16/18-positive cancers, the vaccine costs and clinical costs. Observed combinations of these parameters in different countries show a decrease in the CER between 10% and 31%.
European journal of cancer (Oxford, England: 1990) 10/2010; 47(3):428-35. DOI:10.1016/j.ejca.2010.09.030 · 4.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Discounting is a widely accepted practice in cost-effectiveness analysis to weigh future costs and effects for their timing. In 2006, the Dutch Health Care Insurance Board revised its recommended rates for discounting. They recommended differential discounting of costs and effects, whereby effects are discounted at a lower rate relative to the costs. The question is whether this guideline is to be generally used for decision-making in the Netherlands. We show how the use of unequal discount rates leads to confusing cost-effectiveness results and why further implementation guidelines are essential.
Nederlands tijdschrift voor geneeskunde 01/2010; 154:A1970.
[Show abstract][Hide abstract] ABSTRACT: Cervical cancer incidence and mortality can be reduced substantially by organised cytological screening at 3 to 5 year intervals, as was demonstrated in the Nordic countries, the United Kingdom, the Netherlands and parts of Italy. Opportunistic screening, often proposed at yearly schedules, has also reduced the burden of cervical cancer in some, but not all, of the other old member states (belonging to the European Union since 1995) but at a cost that is several times greater. Well organised screening programmes have the potential to achieve greater participation of the target population at regular intervals, equity of access and high quality. Despite the consistent evidence that organised screening is more efficient than non-organised screening, and in spite of the Cancer Screening Recommendations of the European Council, health authorities of eight old member states (Austria, Belgium, France, Germany, Greece, Luxembourg, Portugal and Spain) have not yet started national organised implementation of screening for cervical cancer. A decision was made by the Irish government to extend their pilot programme nationally while new regional programmes commenced in Portugal and Spain. Introduction of new methods of prevention, such as HPV screening and prophylactic HPV vaccination, can reduce the burden further, but this will require a high level of organisation with particular attention needed for the maximisation of population coverage, compliance with evidence-based guidelines, monitoring of data enabling continued evaluation and improvement of the preventive programmes.
European journal of cancer (Oxford, England: 1990) 09/2009; 45(15):2671-8. DOI:10.1016/j.ejca.2009.07.016 · 4.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the Netherlands, low cervical cancer incidence and mortality rates might limit the cost-effectiveness of vaccination against the human papillomavirus (HPV). We examined the effect on cervical cancer incidence and mortality of adding HPV vaccination to the current Dutch cervical cancer screening situation and calculated the cost-effectiveness.
Costs and effects were estimated under favorable assumptions (ie, that HPV vaccination provides lifelong protection against 70% of all cervical cancers, has no side effects, and is administered to all women regardless of their risk of cervical cancer) by using the microsimulation screening analysis (MISCAN) model. The impact of changes in the price of vaccination, number of booster vaccinations, vaccination attendance rate, vaccination efficacy, cervical cancer incidence level, and quality-of-life assumptions was investigated in sensitivity analyses.
Using the current price of euro118 per vaccine dose and with discounting of costs and effects at an annual rate of 3%, adding HPV vaccination to the current Dutch screening situation had a cost-effectiveness ratio of euro53 500 per quality-adjusted life-year (QALY) gained. The threshold price per vaccine dose at which the cost-effectiveness of vaccination would correspond to an acceptability threshold of euro20 000 per QALY gained was euro40. With the addition of one or more (up to four) booster vaccinations during a lifetime, this threshold price decreased to euro33 for one booster (to euro16 for four boosters). With a doubling of the cervical cancer incidence level, the cost-effectiveness ratio was euro24 400 per QALY gained and the maximum price per dose at threshold of euro20 000 was euro97. All threshold prices were lower under less favorable effectiveness assumptions.
In the Netherlands, HPV vaccination is not cost-effective even under favorable assumptions. To become cost-effective, the vaccine price would have to be decreased considerably, depending on the effectiveness of the vaccine.
[Show abstract][Hide abstract] ABSTRACT: Recommendations for the age to initiate cervical cancer screening should be directed towards maximum detection of early cervical cancer. However, the screening programme should do more good than harm. The aim of this analysis was to determine whether the target age for cervical cancer screening should be lowered in view of apparent increases in new cases of invasive cancer below age 30 and in age group 30-44 years in The Netherlands. Therefore, all cervical cancer cases diagnosed between January 1, 1989 and December 31, 2003 were selected from the nationwide population-based Netherlands Cancer Registry. For age group 25-39 years, incidence data were also available for 2004 and 2005. To describe trends, the estimated annual percentage of change and joinpoint analysis were used. Between ages 25 and 28 years, the absolute number of new cases of cervical cancer annually has varied between 0 and 9 per age. Significantly decreasing trends in incidence were observed for age groups 35-39 and 45-49 (p < 0.0001 and p = 0.01, respectively). The annual number of deaths fluctuated with a decreasing trend for age groups 30-34 and 35-39 years (p = 0.01 and p = 0.03, respectively). Because the incidence and mortality rates for cervical cancer among women younger than 30 are low and not increasing, lowering the age for cervical cancer screening is not useful at this time. Although the number of years of life gained is high for every case of cervical cancer prevented, the disadvantages of lowering the screening age would be very large and even become disproportionate compared to the potential advantages.
International Journal of Cancer 09/2008; 123(6):1403-6. DOI:10.1002/ijc.23652 · 5.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Over the past decades, incidence trends of colorectal cancer are sharply increased in Singapore. In this population-based study we describe changes in colorectal cancer incidence in Singapore and explore the reasons behind these changes through age-period cohort (APC) modeling.
We included all 22,609 colorectal cancer cases reported to the Singapore Cancer Registry between 1968 and 2002. Poisson regression, using age-period (AP) and age-cohort (AC) models was used to determine the effects of age at diagnosis, calendar period, and birth cohort.
Male colorectal cancer rates between 1968 and 2002 from 20 to 40 per 100,000 person years. The increase was sharpest among older men, for whom there was a significant AC effect. Female colorectal cancer rates increased until 1992 (from 16 to 29 per 100,000 person years) and stabilized afterward. For women under 65 years, we observed a significant AP effect, corresponding to a sudden rise in colorectal cancer incidence around 1978.
This study demonstrates important gender differences in colorectal cancer incidence in Singapore, with increasing rates among men, and stabilized rates in women. The increase in men is mainly attributable to an incidence increase in the oldest age groups, probably due to increased exposure to dietary and lifestyle risk factors earlier in life. The stabilization in female colorectal cancer risk could be due to lower exposure to lifestyle risk factors and prophylactic removal of precancerous lesions.
International Journal of Colorectal Disease 06/2008; 23(5):461-7. DOI:10.1007/s00384-007-0421-9 · 2.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Despite increased recognition of the importance of investigating socio-economic inequalities in health from a life course perspective, little is known about the influence of childhood socio-economic position (SEP) on cancer incidence. The authors studied the association between father's occupation and adult cancer incidence by linking information from the longitudinal GLOBE study with the regional population-based Eindhoven Cancer Registry (the Netherlands) over a period of 14 years. In 1991, 18,973 participants (response rate 70.1%) of this study responded to a postal questionnaire, including questions on SEP in youth and adulthood. Respondents above the age of 24 were included (N=12,978). Cox regression was used to calculate hazard ratios (HR) for all cancers as well as for the five most frequently occurring cancers by respondent's educational level or occupational class, and by father's occupational class (adjusted for respondent's education and occupation). Respondents with a low educational level showed an increased risk of all cancers, lung and breast cancer (in women). Respondents with a low adult occupational level showed an increased risk of lung cancer and a reduced risk of basal cell carcinoma. After adjustment for adult education and occupation, respondents whose father was in a lower occupational class showed an increased risk of colorectal cancer as compared to those with a father in the highest social class. In contrast, respondents whose father was in a lower occupational class, showed a decreased risk of basal cell carcinoma as compared to those with a father in the highest occupational class. The association between childhood SEP and cancer incidence is less consistent than the association between adult SEP and cancer incidence, but may exist for colorectal cancer and basal cell carcinoma.
Social Science & Medicine 04/2008; 66(5):1131-9. DOI:10.1016/j.socscimed.2007.11.035 · 2.56 Impact Factor